Fiberglass spray gun



NOV. 1963 J. w. UNDERDOWN ETAL 3,111,272

FIBERGLASS span cum Filed Sept. 28, 1959 2 Sheets-Sheet 1 Fig.

Z t Z John W. Underdown John E. E hernberger INVENTORS 1963 J. w.UNDERDOWN ETAL 3,111,272

FIBERGLASS SPRAY GUN Filed Sept. 28, 1959 2 Sheets-Sheet 2 IIIILI MIIJohn W Underdawn John E. E hernberger INVENTORS BY ma Wzwey FM UnitedStates Patent Oil" 3,1 1 1,272 Patented Nov. 19, 1953 3,111,272 FBERGLASPRAY GUN John W. Underdown, 1844 Linden St, and John E. Ehernberger,1035 /2 Rose Sh, both of Sydney, Nebr.

Filed Sept. 28, 1959, Ser. No, 842,755 2 Claims. ((31. 239-420 Thisinvention relates to fiberglass spray guns and more particularly toimprovements in such equipment making the operation of the gunconsiderably more economical and clean.

An object of the invention is to provide a spray gun of the type forspraying a mixture of liquid plastic and chopped roving, usuallyfiberglass, onto a surface of a mold or preform to make various shapesand objects. Specifically, the invention improves the operation of suchguns by a chopped roving tube having a discharge end through which thechopped roving is propel-led under air pressure so that the choppedparticles are directed into the issuing stream or streams of syntheticresin without relying on gravity feed or the mere attraction of theroving to the issuing jets of resin.

Briefly, the invention is preferably embodied in a gun which has a pairof conventional gun sections arranged at an angle to each other so thatthe spray of synthetic resin merges to an apex. The frame of the gun isequipped with a chopped roving tube and has an air line or at least, aport through which air under pressure enters the tube. The high pressureair entering the tube cooperates with the walls of the tube to form alow pressure area at the inlet of the tube which is in registry with theroving cutting mechanism of the gun. This sucks the cut roving into thetube and the same air blast propels the roving suspended therein untilit merges and meets the streams of synthetic resin from the conventionalgun sections.

The advantages of the invention are that the chopped roving and liquidplastic, ordinarily a synthetic resin, are thoroughly mixed. A veryminor fraction of the chopped roving, ordinarily fiberglass, is wastedwhereas, in other conventional guns which are commercially available, avery important percentage of the chopped fiberglass is lost, ordinarilyin the order of 35% to 40%, inasmuch as it falls to the fioor and/ or isnot thoroughly mixed with the liquid plastic. The roving losses havebeen so materially reduced by the invention, which is to be consideredas either original equipment or an attachment for existing guns, thatthe losses are in the order of 1%.

These together with other objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout, and in which:

FIGURE 1 is a top view of a gun equipped with means to practice theinvention.

FIGURE 2 is a side view of the gun in FIGURE 1.

FIGURE 3 is a front view of the gun in FIGURE 1.

FIGURE 4 is a largely diagramamtic view showing the principal parts ofthe invention.

In the accompanying drawings there is illustrated a gun havingconventional gun sections 12 and 14 carried by frame 16 from whichhandle grip 18 depends. There is a trigger 20 to actuate theconventional guns, each of which is arranged to issue a stream of liquidsubstance, usually a synthetic resinous plastic in a spray patternwherein streams 22 and 24 issue from the gun nozzles in a coplanarrelation, but they converge at a slight distance in advance of thenozzles of the gun sections 12 and 14. Lines 26 and 28 are operativelyconnected with the gun sections and are under the control of the trigger2a. In-

asmuch as the gun sections and the arrangement of the gun so fardescribed is conventional, further detail is not given. Additionalconventional parts include resilient roller 30 mounted for rotation on aspindle 32 that is mechanically carried by the frame of the gun. Idlerroller 34 is located adjacent to resilient roller 30 and there is acutter roller 36 with removable blades, driven by a motor-transmissionunit 33, also attached to the frame of the gun. Roving 4t ordinarilylong fiberglass strands, is fed through guide 42 carried by frame 16 andbetween rollers 30 and 34. Roller St is turned by the blades of roller36, and the roving is chopped into short lengths thereby.

Ordinarily, the chopped roving is fed by gravity flow or by a slightpropulsion as can be obtained by the rotation of cutter roller 36,forwardly of the gun and into the merging streams 22 and 24. But, thisresults in considerable loss of chopped roving and poor mixture with theliquid plastic that is discharged from the gun sections 12 and 14. Thisproblem is overcome by means of an attachment 5% shown best in FIGURE 4.The mechanism shown in this figure is considered an attachment since itmay be installed as a conversion device for existing guns. Further, itis to be clearly understood that attachment 50 may be used as originalequipment in the manufacture of guns without alteration as to principleand function.

Attachment 50 consists of a tube 5 2 having an open discharge end 54 andan open inlet end 56. The tube has a curved part 50 that turns upwardlyfrom the longitudinal axis of the balance of tube 52, this balance ofthe tube represented at 6!} and made of a straight portion. The upperedges 62 of the inlet 56 may be contoured to follow the contours ofrollers 30 and 36 at the lower peripheries thereof, but it is to benoted from FIGURE 4 that the inlet 56 is in direct registry with thechopped roving which is discharged from the cutter roller 56. The inletend of tube 52 functions as a funnel to receive this chopped rovingwhile the balance of the tube functions to direct the chopped rovingforwardly and in the same general direction as the streams 22 and 24.

There are means for adjusting the elevation of the tube 50'. One end ofthe tube is suitably supported, for instance by a mechanical swivel orsimply by air line 64 having an inherent amount of flexibility, e.g. acopper line. The opposite part of the tube is adjustable by turning anadjust ment nut 66 carried by adjustment screw 68. The upper end of theadjustment screw is secured to the lower part of tube 52, and theadjustment screw extends through an aperture in a bracket 79 attached toor forming a part of the base or frame 16 of the gun. In FIG. 4, turningnut 66 in one direction will lower the discharge end 54 of the tubeagainst the yielding opposition of the supporting air line 64. Turningthe adjustment nut in the opposite direction will leave the tube free tobe elevated by the inherent resilience in line 64. More positive meansfor achieving this adjustment would include a simple addition of anothernut on the screw 68; swivelly connecting screw 68 to tube 52 andthreading the screw in a tapped opening in bracket 7 0; providingentirely diiferent types of mechanical adjustments, etc.

Air line 64 has a control valve 76 therein and is connected with anexternal supply of air under pressure. When air blows under pressurethrough port 78 at the curved part of tube 52, the air forms a venturiaction, sucking the cut roving through the inlet 56 and expelling itunder pressure through the discharge end 54 of the tube. The axis of thestraight part of the tube is approximately coplanar with the dischargeaxes of sections 12 and 14 so that the chopped roving merges with thestreams 22 and 24 of plastic and thoroughly mixes therewith. Any lossesof chopped roving are negligible, and the chopped roving has the greatadvantage of being more thoroughly mixed with the liquid plastic.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention asclaimed.

What is claimed as new is as follows:

1. -A manually operable portable spray gun comprising power operatedchopping means for cutting roving, a frame supporting said means, a pairof gun sections adapted to discharge plastic in a pair of convergingspray streams mounted in coplanar spaced relationship on said frame, ahollow elongated conduit comprising an arcuate part and a straight partfixed to said frame between said gun sections and coplanar therewith,said conduit being open only at its ends so as to provide a dischargeend and an inlet end, said discharge end being disposed in said straightpart and in proximate alignment with the spray streams, the inlet ofsaid conduit being substantially closed by the chopping means, an airnozzle mounted within said conduit between said ends and in axialalignment with said straight part and pointed toward said discharge endto direct a jet of air towards said discharge end, said jet creating asuction at said inlet whereby air is sucked over said chopping meansthereby cleaning the same and sucking said roving into said conduit,said jet of air further discharging the roving through said dischargeend, and a handgrip connected to said frame and extending transverse tothe plane of said gun sections, one end of said conduit beingresiliently connected to said frame by a resilient tube, one end of saidtube being operatively connected to said air nozzle, the other end ofsaid conduit being connected to said frame by a manually adjustablemechanism whereby said conduit may be properly aligned with said spraystreams.

2. An attachment for a portable spray gun of the type having poweroperated chopping means for cutting roving and a pair of gun sectionsadapted to discharge plastic in a pair of converging spray streamsmounted in coplanar spaced relationship upon a 'frame comprising ahollow elongated conduit including an arcuate part and a straight partfor guiding and discharging said roving into said spray streams, saidconduit being open only at its ends so as to provide a discharge end andan inlet end, said discharge end being disposed in said straight part,an air nozzle mounted within sm'd conduit between its ends and in axialalignment with said straight part and pointed towards said discharge endto direct a jet of air towards said discharge end to discharge theroving and to create a suction effect at the inlet end to suck rovinginto said conduit, means for resiliently connecting the attachment tosaid spray gun frame, said means comprising a resilient tube, one end ofsaid tube being operatively connected to said air nozzle and manuallyadjustable means connecting the other end of the conduit to the frame.

References Cited in the file of this patent UNITED STATES PATENTS2,255,189 Robinson et a1. Sept. 9, 1941 2,328,448 Gustafsson et a1 Aug.31, 1943 2,585,133 Kempthorne Feb. 12, 1952 2,618,817 Slayter Nov. 25,1952 2,702,261 Bacon et al. Feb. 15, 1955 2,787,314 Anderson Apr. 2,1957 2,813,751 Barrett Iov. 19, 1957 2,850,421 Thompson Sept. 2, 19582,854,059 Palmer Sept. 30, 1958 2,860,687 Cole Nov. 18, 1958 2,870,054Amos et a1. Jan. 20, 1959 2,929,436 Hampshire Mar. 22, 1960 2,933,125Anderson Apr. 19, 1960 3,025,195 Kozma Mar. 13, 1962 FOREIGN PATENTS204,774 Austria Jan. 15, 1959 817,875 Great Britain Aug. 6, 1959 560,254Italy Apr. 2, 1957

1. A MANUALLY OPERABLE PORTABLE SPRAY GUN COMPRISING POWER OPERATEDCHOPPING MEANS FOR CUTTING ROVING, A FRAME SUPPROTING SAID MEANS, A PAIROF GUN SECTIONS ADAPTED TO DISCHARGE PLASTIC IN A PAIR OF CONVERGINGSPRAY STREAM MOUNTED IN COPLANAR SPACED RELATIONSHIP ON SAID FRAME, AHOLLOW ELONGATED CONDUIT COMPRISING AN ARCUATE PART AND A STRAIGHT PARTFIXED TO SAID FRAME BETWEEN SAID GUN SECTIONS AND COPLANAR THEREWITH,SAID CONDUIT BEING OPEN ONLY AT ITS ENDS SO AS TO PROVIDE A DISCHARGEEND AND AN INLET END, SAID DISCHARGE END BEING DISPOSED IN SAID STRAIGHTPART AND IN PROXIMATE ALIGNMENT WITHTHE SPRAY STREAMS, THE INLET OF SAIDCONDUIT BEING SUBSTANTIALLY CLOSED BY THE CHOPPING MEANS, AN AIR NOZZLEMOUNTED WITHIN SAID CONDUIT BETWEEN SAID ENDS AND IN AXIAL ALIGNMENTWITH SAID STRAIGHT PART AND POINTED TOWARD SAID DISCHARGE END TO DIRECTA JET OF AIR TOWARD SAID DISCHARGE END, SAID JET CREATING A SUCTION ATSAID LNLET WHEREBY AIR IS SUCKED OVER SAID CHOPPING MEANS THEREBYCLEANING THE SAME AND SUCKING SAID ROVING INTO SAID CONDUIT, SAID JET OFAIR FURTHER DISCHARGING THE ROVING THROUGH SAID DISCHARGE END, AND AHANDGRIP CONNECTED TO SAID FRAME AND EXTENDING TRANSVERSE TO THE PLANEOF SAID GUN SECTIONS, ONE END OS SAID CONDUIT BEING RESILIENTLYCONNECTED TO SAID FRAME BY A RESILIENT TUBE, ONE END OF SAID TUBE BEINGOPERATIVELY CONNECTED TO SAID AIR NOZZLE, THE OTHER END OF SAID CONDUITBEING CONNECTED TO SAID FRAME BY A MANUALLY ADJUSTABLE MECHANISM WHEREBYSAID CONDUIT MAY BE PROPERLY ALIGNED WITH SAID SPRAY STREAMS.